*{
    margin: 0;
    padding: 0;
}
a{
    text-decoration: none;
}
body{
    padding: 20px;
    padding-right: 100px;
}
.box{
    width: 100%;
    height: 10000px;
    >div{
        margin-bottom: 20px;
    }
    .header{
        height: 500px;
        background-color: yellowgreen;
    }
    .item{
        width: 100%;
        height: 200px;
        background-color: red;
    }
}
.nav{
    width: 50px;
    position: fixed;
    top: 50%;
    right: 10px;
    .navItem{
        display: block;
        width: 50px;
        height: 50px;
        font-size: 12px;
        width: 100%;
        background-color: yellowgreen;
        margin-bottom: 5px;
        display: flex;
        justify-content: center;
        align-items: center;
        &.active{
            color: red;
        }
    }
}